Biology Paper 2!

Question 1

Homeostasis

Answer 1

the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal or external changes

Question 2

RP7: Reaction times

Answer 2

1. person 1 sits on a stool and stretches their arm across a table with their hand overhanging the edge
   person 2 holds a ruler vertically with the zero measurement between person 1’s thumb and forefinger
2. person 2 drops the ruler at a random time
   person 1 has to catch the ruler by pinching their fingers together as quickly as possible
3. the measurement at the top of the thumb is recorded
4. this is repeated with the same person multiple times and a mean is calculated
5. repeat with different people
   IV : person
   DV: reaction time
   CVs: distractions, starting distance, measurements read from the top of the thumb

Question 3

CNS

Answer 3

central nervous system: brain and spinal chord

Question 4

cerebral cortex

Answer 4

highly folded, outer part of the brain
functions:
- language
- memory
- consciousness

Question 5

cerebellum

Answer 5

• controls balance
• co-ordinates movement

Question 6

medulla

Answer 6

• controls heart and breathing rate

Question 7

ways to assess which parts of the brain control what

Answer 7

• assess the changes to patients with brain damage against the area of brain that is damaged
• electrically stimulate certain areas of the brain
• MRI scanning can be used to discover which parts of the brain are active during certain activities

Question 8

what is the eye

Answer 8

• a sense organ
• that contains receptors which are sensitive to colour and light intensity

Question 9

cornea

Answer 9

• a transparent front of the eye
• helps focussing light rays

Question 10

iris

Answer 10

controls the size of the pupil

Question 11

pupil

Answer 11

the hole through which light enters the eye

Question 12

lens

Answer 12

a clear disc that focusses the light rays on the retina

Question 13

retina

Answer 13

contains light sensitive cells

Question 14

ciliary body

Answer 14

contracts to change the shape of the lens

Question 15

suspensory ligaments

Answer 15

holds the lens in place

Question 16

sclera

Answer 16

tough outer layers of the eye

Question 17

optic nerve

Answer 17

carries impulses from the retina to the brain

Question 18

how does the lens of the eye change shape

Answer 18

1. the ciliary muscle contracts/relaxes
2. this tightens (if ciliary relaxes ) or loosens (if ciliary contracts) the suspensory ligaments
3. looser ligaments = thicker lens, tighter ligaments = thinner lens
4. the thicker the lens, the more refracting it is

Question 19

the eye focussing on far vs close objects

Answer 19

• far: ciliary muscle is more relaxed, suspensory ligaments are tighter and lens is thinner since light does not need refracting as much
• close: opposites

Question 20

long-sightedness

Answer 20

• hyperopia
• struggle to focus on nearby objects
• treated with convex lenses
• lens cannot get thick enough

Question 21

short-sightedness

Answer 21

• lens cannot thin out enough
• struggles to focus on distant objects
• treated with concave lenses